System and Method for Evaluating Signal Coupling Between Differential Traces in a Package Design

1. A method for evaluating trace signal coupling of differential signals in an electronic design, comprising the steps of: formulating one or more trace signal coupling rules; processing the electronic design to determine whether trace signal coupling between trace pairs for the differential signals violate the trace signal coupling rules; and generating an indicator associated with the electronic design to identify violated trace signal coupling rules.

2. A method of claim 1 , the step of processing comprising the step of processing one signal net pair of the electronic design for violation of the trace signal coupling rules.

3. A method of claim 1 , the electronic design comprising a package design, the step of formulating comprising the step of formulating one or more group trace signal coupling rules for a group of signal nets of the package design, wherein the step of processing comprises the step of processing the group of signal nets to determine whether inter-trace spacings between differential signal net pairs of the group violate the group trace signal coupling rules.

4. A method of claim 3 , the step of generating comprising the step of generating at least one DRC for one or more violations of the group trace signal coupling rules.

5. A method of claim 1 , wherein the step of formulating one or more trace signal coupling rules comprises defining an inter-trace spacing dimension to ensure signal coupling between the trace pairs, the step of processing comprising the step of determining whether the inter-trace spacing of the trace pairs differs from the inter-trace spacing dimension.

6. A method of claim 5 , the inter-trace dimension comprising about 400 microns.

7. A method of claim 5 , step of formulating comprising the step of defining a tolerance about the dimension.

8. A method of claim 5 , wherein the step of formulating one or more trace signal coupling rules comprises defining a trace segment length difference, between trace pairs in a zone of decoupling, to ensure proper recoupling after the zone of decoupling, the step of processing comprising the step of determining whether trace segment lengths of the trace pairs, in the zone of decoupling, differs from the trace segment length difference.

9. A method of claim 8 , the trace segment length difference comprising about 600 microns.

10. A method of claim 1 , the step of generating an indicator comprising the step of graphically depicting a DRC on a graphical user interface illustrating the electronic design.

11. A method of claim 1 , the step of processing comprising the step of determining a spacing between each of the trace pairs.

12. A method of claim 1 , the electronic design comprising a package design, the trace signal coupling rules defining trace signal coupling for a group of signal nets of the package design.

13. A method of claim 1 , the step of generating an indicator comprising generating a report summarizing violations of the trace signal coupling rules.

14. A method of claim 1 , wherein the step of formulating one or more trace signal coupling rules comprises defining an inter-trace coupling dimension to ensure coupling between trace pairs carrying differential signals, the step of processing comprising the step of determining whether spacing between the trace pairs differs from the inter-trace coupling dimension.

15. A method of claim 14 , the inter-trace coupling dimension comprising about 120 microns.

16. A method of claim 1 , wherein the step of formulating one or more trace signal coupling rules comprises defining a maximum number of times (a) the trace pairs are decoupled and recoupled and (b) the trace pairs have differing trace segment lengths, the step of processing comprising the step of determining whether a number of decoupling and recoupling for the trace pairs, with differing trace segment lengths, exceeds the maximum number.

17. A method of claim 16 , the maximum number comprising about five.

18. A software product comprising instructions, stored on computer-readable media, wherein the instructions, when executed by a computer, perform steps for evaluating trace signal coupling of differential signals in an electronic design, comprising: instructions for determining inter-trace spacing between at least one trace pair for the differential signals; instructions for comparing the spacing to one or more trace signal coupling rules; and instructions for generating an indicator associated with the electronic design to identify violations of the trace signal coupling rules.

19. The software product of claim 18 , further comprising instructions for formulating one or more of the trace signal coupling rules.

20. The software product of claim 18 , further comprising instructions for determining whether one signal net in a group of signal nets has any trace pairs that violate the trace signal coupling rules.

21. The software product of claim 18 , further comprising instructions for generating a report summarizing violations of the trace signal coupling rules.

22. The software product of claim 18 , the instructions for comparing comprising instructions for comparing the spacing to a desired inter-trace dimension set forth in the trace signal coupling rules.

23. The software product of claim 22 , the instructions for comparing comprising instructions for comparing the spacing to the desired inter-trace dimension with a tolerance defined in the trace signal coupling rules.

24. The software product of claim 18 , further comprising instructions for responding to designer inputs to scope the step of determining inter-trace spacing of the at least one trace pair.

25. The software product of claim 18 , the instructions for comparing comprising instructions for comparing the spacing against a trace signal coupling rule defining a dimension of about 120 microns.

26. The software product of claim 18 , the instructions for comparing comprising instructions for comparing the spacing against a trace signal coupling rule defining a decoupling dimension of about 400 microns.

27. The software product of claim 26 , the instructions for comparing comprising instructions for comparing the trace segment lengths of the trace pair, in a zone of decoupling, against a trace signal coupling rule defining a coupling terminated dimension of about 600 microns.

28. The software product of claim 18 , the instructions for comparing further comprising instructions for determining whether respective trace segment lengths of the trace pair within a zone of decoupling differs by a length exceeding a predefined trace segment length difference.

29. The software product of claim 18 , the instructions for comparing further comprising instructions for determining (a) whether respective trace segment lengths of the trace pair within each zone of decoupling differs in length, and (b) whether a number of times the trace pair determined in (a) decouples and recouples exceeds a predefined number.

30. A system for evaluating trace signal coupling of differential signals in an electronic design, comprising: means for formulating one or more trace signal coupling rules; means for processing the electronic design to determine whether trace signal coupling between trace pairs for the differential signals violate the trace signal coupling rules; and means for generating an indicator associated with the electronic design to identify violated trace signal coupling rules.